Stable, optically clear compositions

ABSTRACT

Stable aqueous compositions of biologically active oils for the preparation of optically clear products for use in human or animal healthcare, for example beverages, are prepared.

This application is a 371 of PCT/EP96/04168, filed Sep. 19, 1996.

The present invention relates to a process for preparing compositionscomprising oil soluble ingredients for use in the maintenance and/orpromotion of health. In particular the invention relates to compositionsfor products for internal or external use by humans or animals, such asbeverages and capsules, processes for preparing such compositions andproducts containing them.

WO/94/06310 discloses an aqueous composition for the preparation ofoptically clear products for use in human and animal healthcarecomprising 0.1 to 2.0% of an oil soluble ingredient as a 20-30%dispersion in a suitable oil or 0.1 to 5.0% w/v as the pure crystallinecompound 2-20% of an emulsifier mixture having an HLB value of between10 and 18 or where a blend of emulsifiers is employed, a calculated HLBvalue of between 10 and 18 and 0.1% of an antioxidant or a mixture ofantioxidants.

In “Microemulsions Theory and Practice” (Edited Leon M Prince chapter 3,Academic Press Inc, N.Y., 1977) it is stated that stable microemulsionsresult when an emulsifier is chosen that is chemically matched to theoil. Also in order to form satisfactory emulsions it can be helpful touse two kinds of emulsifier, a primary surfactant and a cosurfactant.

However, a problem encountered with existing compositions has been thestability of emulsions in the presence of certain carbohydrates(particularly syrups) especially those containing polymerised molecules.A particular problem is the formation of occlusion compounds orcomplexes on long term (several months) storage.

We have now found that a composition having enhanced bioavailability andstability in syrup can be obtained by using an emulsifier mixturecomprising fatty acid residues which chemically matches the fatty acidresidues of the oil soluble ingredient or a dispersion of the oilsouluble ingredient and using specific ratios of oil or oil dispersionto emulsifier and specific ratios of primary to cosurfactant.

Accordingly the present invention provides a process for preparing anaqueous composition for the preparation of optically clear productshaving enhanced stability in syrup and bioavailability for human oranimal healthcare comprising a) mixing 0.001-2.0% of an oil solubleingredient or 0.1-2.0% w/w of an oil soluble ingredient as a 20-30%dispersion in a suitable oil with 2-10% of an emulsifier mixture havingan HLB (hydrophilic lipophilic balance) value of between 10 and 18 andheating to between 25 and 150° C. so as to yield a transparent mixtureb) combining the mixture with water while continuously stirring toprovide a transparent composition characterised in that the emulsifiermixture is a combination of a primary surfactant and a secondary orcosurfactant, wherein the fatty acid profile of the emulsifier mixturematches the fatty acid profile of the oil soluble ingredient or thedispersion of an oil soluble ingredient, the HLB of the primarysurfactant is greater than the cosurfactant and the weight ratio of oilor oil dispersion to emulsifier is between 1:1 and 1:7 and the ratio ofprimary to cosurfactant is between 10:1 and 200:1.

Preferably the ratio of oil or oil dispersion to emulsifier is between1:1 and 1:5. Preferably the ratio primary to cosurfactant is between20:1 and 50:1, and is most suitably about 30:1.

Suprisingly, in addition to solving the problem of the formation ofocclusion complexes, it has been found that by including a small amountof a cosurfactant allows less overall emulsifier is used. This isparticularly valuable in the case of syrup containing beverages wherereducing emulsifier content has cost and taste benefits and reduces theamounts of ‘synthetic’ components.

The present invention allows the formation of stable compositions insyrups which are typically up to 60 Brix, using very low amounts ofemulsifier. This is particularly useful in the formulation of productsespecially energy drinks and capsules where excess amounts ofemulsifiers along with carbohydrates can lead to the formation ofocclusion products during long term (several months) storage.

An important advantage of the compositions of the present invention overknown compositions is one of economy since it allows products withminimal amounts of emulsifiers to be developed. The compositions areparticularly useful for incorporation of biologically active oils intoaqueous preparations in a microdispersed form that facilitates uptake.

Preferably the mixture in a) is added to the water. Preferably one ormore antioxidant(s) is first dispersed with the emulsifiers in a).Suitably the oil soluble ingredient is a biologically active oil bywhich we mean natural or synthetic oils which are or containbiologically active agents in particular prophylactic or therapeuticagents.

The composition of the present invention is able to yield a product withdesirable properties, particularly high water solubility, usingingredients which have hitherto been found to be difficult to solubilisesatisfactorily in this kind of product.

Preferably the biologically active oil is an oil of natural origin forexample from the seeds or flowers of the Ribes, Boraginaceae, Labiataea,Onagraceae and Curcubitaceae species, oils of fungal origin, fish oilsor other natural oils. Preferred oils include evening primrose oil,borage/starflower oil and blackcurrant seed oil. Preferably the oilsoluble ingredient comprises a colouring ingredient.

Compositions containing β carotene as an oil soluble ingredient havebeen particularly successful. Particularly suitable sources of βcarotene include both natural and synthetic β carotene as dispersions inoil (as available from various commercial sources including thosementioned herein).

Suitably the amount of oil is 0.001-2.0%, preferably 0.1-1.0% by weightexpressed as the pure substance. Oils for use in the present inventioncan be extracted from natural sources by processes known in the art. Theoils are commercially available, for example, from Sigma Chemical Co.,Poole, Dorset. The compositions can contain more than one biologicallyactive oil.

Other biologically active ingredients can be used in the compositionaccording to the invention, in particular carotenoid pigments eg.β-carotene to produce a useful combination of colour and nutritionalbiochemicals.

The biologically active oils may be mixed or dispersed with othersuitable oils in particular, consumable oils for example, corn, peanut,safflower, olive and rapeseed oils as well as many essential oilsparticularly those used in beverages used to give flavours, such ascitrus oils.

The emulsifiers may be any anionic, cationic, amphoteric or non-ionicemulsifier which are suitable for consumption by or application to thehuman or animal body. Preferably the emulsifiers are non-ionicemulsifiers having an HLB (hydrophilic/lipophilic balance) of 12-16 andmost preferably has an HLB value of 15. Preferred mixtures include Tween80 (polyoxyethylenesorbitan monooleate) and Span 80 (sorbitanmonooleate) available from ICI Speciality Chemicals, Leatherhead, Surreyor from Sigma Chemical Company, Poole, Dorset.

Suitably the emulsifier mixture is a binary or tertiary blend ofemulsifiers, for example blends of Tween 60 with a sucrose esteremulsifier (manufactured by Mitsubishi Kasei Food Corporation. IchikawaBuilding, 13-3 Ginza 5-Chome, Chuo-ku, Tokyo 104, Japan) or blends ofTween 60 and sucrose ester and a polyglycerol ester of a fatty acid(available from Grindsted Products Limited., Northern Way, Bury St.Edmunds, Suffolk).

The amount of emulsifier mixture in the composition is selected as anamount which will vary depending upon which specific biologically activeoil is used, its method of preparation, and how much is included. Forexample an oil-based dispersion containing 1% by weight of biologicallyactive oil will generally require an emulsifier mixture in the range of1-8-% w/w to achieve a clear dispersion and so as not to havesignificant adverse flavour effects in typical products when diluted.

Preferably the emulsifier mixture comprises a polysorbate, in particularpolysorbate 60 in the case of consumable products as it has theadvantage of having the least noticeable taste. Therefore, aparticularly useful feature of the present invention is the ability toproduce a flavourless composition.

The composition advantageously comprises in addition an antioxidantwhich can be for example, alpha-tocopherol, tocopheryl acetate, ascorbicacid, ascorbyl palmitate, butylated hydroxyanisole (BHA) and butylatedhydroxytoluene (BHT) or a mixture of such antioxidants. Particularlypreferred antioxidants are α-tocopherol, tocopheryl acetate, ascorbylpalmitate and ascorbic acid.

Whilst the present invention is particularly useful in the production ofoptically clear products, the present invention can also be used toprepare opaque, cloudy products. A frequent problem with such products,particularly those products containing emulsified oils is that of ‘neckringing’. The compositions prepared according to the present inventionhave been found not to exhibit this problem. It will be appreciated thatthe compositions of the present invention may be used for products inthe pharmaceutical or veterinary field other than beverages, such asvitamin and cough syrups, throat sprays, lotions and mouthwashes,particularly where optical clarity is important.

Certain biologically active oils contain vitamins and provitamins suchas vitamins A, D, E, carotenoid pigments and nutritionally importantfatty acids.

In the compositions of the present invention the biologically activeoils are believed to be finely dispersed in a micellar form or asmicroemulsions because they exhibit certain characteristics eg.transparency when viewed by transmitted light. Therefore a furtheradvantage of the compositions according to the present invention is thatthe fine dispersion of these oils in aqueous preparations will help topromote their efficient uptake by body tissues when the composition ispresented to the body. Whilst the small particle size of the particlesof biologically active oils favour their uptake, the simultaneouspresentation or ingestion of the oils with an emulsifier will alsoencourage efficient transfer of these substances across membranes.

The formulations according to the invention also have acid resistance.This is advantageous because prior to absorption from the intestinaltract, the preparation is able to survive the strongly acid conditionsof the stomach.

In a further aspect of the invention there is provided a method ofadministration of an oil-soluble material to human or animal body bytreating said body with a composition according to the invention.Preferably the composition is administered orally, for example in theform of a liquid composition.

The composition obtained according to the present invention is anaqueous dispersion which is capable of dissolution in water-basedproducts to yield optically clear finished products. It will beappreciated that further ingredients may optionally be included in thecomposition of the present invention or to the final food product, forexample sweeteners, preservatives (eg. sulphur dioxide, benzoic acid andsorbic acid), proteins, fats, vitamins, minerals and other materialsemployed in the preparation of food and drink products. Optionally thecompositions also contain antioxidant cofactors such as zinc, seleniumand manganese which are needed for the body's naturally occurringantioxidant enzymes. Preferably the final product is flavoured; this canbe achieved by the addition of naturally flavoured foods such as fruitjuices and concentrates, extracts and compounds or flavouring additives.Preferably further nutritive ingredients are added to the final drinksuch as other vitamins and minerals as described in “The Food LabellingRegulations 1984” Statutory Instrument No. 1305 (1984) H.M.S.O., London.

Suitably processing aids can be incorporated. Such aids may includeingredients which influence pH, redox potential, enzyme activity,hydrogen bonding and/or other aspects. Processing aids are for examplesulphur dioxide, other antioxidants, metal salts, acids (eg. phosphoricand citric acid), alkalis, surfactants such as lecithin and starchplasticisers eg. calcium chloride. Preferred processing aids forinclusion are anti-foaming agents eg. silicones.

Ingredients subject to a loss of nutritional value are added at a latestage of the process. Optionally the product can be produced in light oroxygen excluding containers after preparation to increase protection ofmaterials sensitive to light or oxygen induced degradation. Optionallythe product can be carbonated.

The use of these high temperatures incurs the risk of degradation of theoil unless suitable precautions are taken. For example it is desirableto exclude oxygen by heating the mixture in an atmosphere of nitrogen.In a further aspect of the present invention additional water is addedto the composition to yield an aqueous intermediate product which issuitable for use in a suitable water-based product.

In a further aspect of the invention there is provided the use ofcarotene microemulsions to deliver high bioavailability carotenes to theblood and to tissues for use in medicine. The invention is illustratedby the following Examples.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: Contour plot of microemulsion clarity.

FIG. 2: Response surface of microemulsion clarity.

FIG. 3: Contour plot of microemulsion clarity after one hour in syrup.

FIG. 4: Response surface of mocroemulsion clarity after one hour insyrup.

FIG. 5: Beta-carotene serum concentrations for 11 days post dose.

EXAMPLES

Experiments were carried out to develope compositions with maximumstability and clarity in syrup. Primary surfactants of high HLB valueswere selected so as to chemically match as far as possible the oilpresent in the composition. For example, in the following compositionswhere β-carotene (30% dispersion) is dispersed in a vegetable oil richin oleic acid, emulsifiers rich in oleic acid residues were used. Thechosen primary surfactants were initially screened by preparingmicroemulsions which comprised a large excess of emulsifiers. While somemicroemulsions were opaque others were transparent. Using the primarysurfactants producing transparent microemulsions, a number ofco-surfactants were selected. These were of lower HLB values but similarin chemical composition to the respective primary surfactants. It wasfound that the inclusion of a small amount of particular cosurfactantsenabled the amount of total emulsifier to be reduced and resulted inimproved stability of the microemulsion.

The ratio of primary surfactant to cosurfactant was determined bypreparing a series of phase diagrams that graphically represent how thecomposition is related to the transparency of the microemulsion, so asto provide enough information to optimise the composition further.Further experiments were then designed to optimise the microemulsions. Astatistical approach [e.g Box, G. E. P., Hunter, W. G. and Hunter. J. S.(1978) Statistics for Experimenters] allowed a reduction in the totalnumber of experiments required. The results generated were plotted outusing “Minitabs for Windows” statistics software (Version 10, MinitabInc., State College, Pa. USA).

The clarity of each microemulsion was determined by measuring thetransmission of light at 800 nm through each microemulsion. A polynomialequation was generated that could then be used to explain therelationship between the composition of the microemulsions and theirclarity. This equation was used to generate the contour and responsesurfact plots shown in FIGS. 1 and 2. To determine the optimumcomposition for optimum stability in syrup a similar approach was used,but after preparation of each microemulsion a small proportion was addedto syrup, heated to 70 degrees C., cooled and the clarity determined. Apolynomial equation was generated to explain the relationship betweenmicroemulsion composition and clarity. This was used to generate thecontour and response plots of microemulsion clarity after one hour insyrup. As can be seen from comparing plots in FIGS. 3 and 4 with thosein FIGS. 1 and 2 the compositions which afford optimum clarity afterheating in syrup is not the same as those in the absence of syrup.

Example 1.1—Composition

% w/w β-carotene * (30% dispersion) 0.3 emulsifier (polysorbate 80) 3.5emulsifier (sorbitan monooleate) 0.7 water to 100 * From F. Hoffman-LaRoche, Basel, Switzerland. Tradename β carotene 30% FS.

The β-carotene is dispersed in the two emulsifiers and the mixture isheated to 140° C. with stirring. At this point the mixture should remaintransparent. Finally, the mixture is combined with hot water and thencooled rapidly.

The contour and response surface plots in FIGS. 1 and 2 show thecompositions of polysorbate 80 and sorbitan mono oleate that are neededto produce microemulsions with maximum clarity.

The emulsifier mixture satisifies the formula:

% Transmission=−59.4+63.8 (Tween 80 g/100 g0)+169 (Span 80 g/100 g)−9.16(Tween 80 g/100 g)² −119 (Span 80 g/100 g)²

Example 1.2—Colour Composition for Maximum Stability in Syrup

% w/w β-carotene * (30% dispersion) 0.33 emulsifier (polysorbate 80) 5emulsifier (sorbitan monooleate) 0.15 water to 100 * See example 1.1

The β-carotene is dispersed in the two emulsifiers and the mixture isheated to 140° C. with stirring. At this point the mixture should remaintransparent. Finally, the mixture is combined with hot water as detailedin Example 1.1. These compositions have been stable for 1 year.

The contour and response surface plots in FIGS. 3 and 4 show thecompositions of polysorbate 80 and sorbitan mono oleate required toproduce microemulsions with maximum stability when added to a syrupconcentrate.

The resulting clarity is defined by the equation:

% transmission=−5.2+32.5 (Tween 80% W/W)+51 (Span 80% W/W)−3 (Tween 80%W/W)²−159 (Span 80% W/W)²

Example 1.3—β-carotene Composition Used in Bioavailability Study(Example 2)

% w/w β-carotene * (30% dispersion) 0.45 emulsifier (polysorbate 60) 6emulsifier (sucrose stearate) 0.7 water to 100 * See example 1.1

The β-carotene is dispersed in the polysorbate 60 and the mixture isheated to 140° C. with stirring. The sucrose stearate is added withcontinued stirring until the mixture is transparent. The mixture is thenadded to hot water as detailed in example 1.1.

Example 1.4—Manufacture of Flavoured Cconcentrate for Bottling

A flavoured concentrate is prepared by mixing the following ingredientstogether with stirring. The flavourings and microemulsion compositionare added last.

% w/w Glucose syrup (S.G 1.4) 63.27 Preservatives 0.07 Acidulants 0.89flavourings 0.03 water 35.45 β-carotene microemulsion composition 0.28Total 100.00

The quality criteria are;

Refractometric soluble solids, °Brix of 50.8±0.5

Acidity, expressed as citric acid 0.76±0.04% w/w

The flavoured concentrate is pasteurised at 91° C.±2° C. for 42±3seconds and cooled to below 30° C. One part flavoured concentrate isdiluted with 2.25 parts water prior to bottling. In this example themicroemulsion composition contains 0.45% w/v β-carotene and the finishedproduct contains 4.5 mg β-carotene per litre.

The concentration of biologically active oil in the finished product canbe changed by varying the microemulsion composition and/or by varyingthe amount of microemulsion composition that is added to the flavouredconcentrate.

Example 2

Bioavailability study

A comparison was made of the bioavailability, in healthy volunteers ofthe microemulsion β-carotene preparation as described in Example 1.2with a conventional dispersion preparation prepared using a β carotenewater dispersible powder (tradename BETATENE, 2.5%, available fromHenkel Ireland Ltd, Cork, Ireland). The preparations were drinkscontaining 15 mg of β carotene in 250 mls (as in Example 1.2). A placebowas included that looked and tasted the same as the other two productsbut contained no β carotene.

Recipes for the three variants used in the comparative bioavailabilitystudy Microemulsion Dispersion drink Placebo drink preparationpreparation Ingredient (g/l) (g/l) (g/l) glucose syrup 239.42 239.42239.42 flavourings 0.12 0.12 0.12 sodium benzoate 0.28 0.28 0.28ascorbic acid 0.25 0.25 0.25 lactic acid 0.97 0.97 0.97 citric acid 1.751.75 1.75 caffeine 0.09 0.09 0.09 sunset yellow 0.056 — — β carotene as— 0.06 — microemulsion β carotene as — — 0.06 dispersion water to volume

Specification for the three products

Brix 18.0±0.2°

Acidity 0.29±0.03% W/W (expressed as citric acid monohydrate)

Subjects received a single 250 ml serving of either the placebo or themicroemulsion drink or the dispersion drink according to a Latin squarerandomisation schedule.

Blood samples were initially collected weekly for three weeks pre-doseand then at appropriate times for 11 days post-dose. Serum was analysedfor β-carotene using a fully validated HPLC method. The treatmentperiods were separated by nine days.

FIG. 5 shows the β-carotene serum concentration for the 11 days postdose for the two test preparations and placebo.

The microemulsion and dispersion preparations were found to be differentin both the mean maximum serum beta-carotene concentration and the areasunder the curves. Both these differences were significant at the 0.1%level. From this it is concluded that β-carotene is significantly morebioavailable when administered as a microemulsion compared to aconventional dispersion.

What is claimed is:
 1. A process for preparing an aqueous compositionused in the preparation of optically clear products comprising a) mixing0.1-2.0% w/w of an oil soluble ingredient as a 20-30% w/w dispersion ina consumable or essential oil, with 2-10% w/w of an emulsifier mixturehaving an HLB (hydrophilic lipophilic balance) value of between 10 and18 and heating to between 25 and 150° C. so as to yield a transparentmixture; b) combining the transparent mixture with water whilecontinuously stirring to provide a transparent composition wherein theemulsifier mixture is a combination of a primary surfactant and asecondary or cosurfactant, wherein the fatty acid profile of theemulsifier mixture matches the fatty acid profile of the dispersion ofthe oil soluble ingredient, the HLB of the primary surfactant is greaterthan the cosurfactant and the weight ratio of the dispersion of the oilsoluble ingredient, to emulsifier mixture is between 1:1 and 1:7, andthe ratio of primary to cosurfactant is between 10:1 and 200:1.
 2. Aprocess according to claim 1 wherein in the emulsion mixture is added tothe water.
 3. A process according to claim 1 wherein one or moreantioxidants is first dispersed in the emulsifier mixture.
 4. An aqueouscomposition for the preparation of optically clear products for use inhuman or animal healthcare obtained by the process of claim
 1. 5. Acomposition as claimed in claim 4 wherein the ratio of primary tocosurfactant is between 20:1 and 50:1.
 6. A composition as claimed inclaim 5 wherein the ratio of primary to cosurfactant is about 30:1.
 7. Acomposition as claimed in claim 4 wherein the amount of oil solubleingredient is 0.1-1.0%.
 8. A composition as claimed in claim 4 whereinthe amount of emulsifier is less than 6%.
 9. A composition according toclaim 11 wherein the amount of antioxidant is 0.3-0.5%.
 10. A method ofadministering an oil-soluble material to a human or animal in needthereof, which method comprises administering to said human or animal anoptically clear aqueous composition according to Claim
 4. 11. Acomposition according to claim 4 which further comprises one or moreantioxidants.
 12. A composition according to claim 11 in which theantioxidant is ascorbic acid or alpha-tocopherol or a mixture thereof.13. A composition according to claim 4 wherein the ratio of primarysurfactant to cosurfactant is between 20:1 and 50:1.
 14. A compositionaccording to claim 13 wherein the ratio of primary surfactant tocosurfactant is about 30:1.
 15. A process for preparing an aqueouscomposition used in the preparation of optically clear productscomprising a) mixing 0.001-2.0% w/w of an biologically active oil with2-10% w/w of an emulsifier mixture having an HLB (hydrophilic lipophilicbalance) value of between 10 and 18 and heating to between 25 and 150°C. so as to yield a transparent mixture; b) combining the transparentmixture with water while continuously stirring to provide a transparentcomposition wherein the emulsifier mixture is a combination of a primarysurfactant and a secondary or cosurfactant, wherein the fatty acidprofile of the emulsifier mixture matches the fatty acid profile of theoil, the HLB of the primary surfactant is greater than the cosurfactantand the weight ratio of oil, to emulsifier mixture is between 1:1 and1:7, and the ratio of primary to cosurfactant is between 10:1 and 200:1.16. The process according to claim 15 wherein the emulsion mixture isadded to the water.
 17. The process according to claim 15 wherein one ormore antioxidants is first dispersed in the emulsifier mixture.
 18. Anaqueous composition for the preparation of optically clear products foruse in human or animal healthcare obtained by the process of claim 15.19. The composition according to claim 18 wherein the compositionfurther comprises a colouring ingredient.
 20. The composition accordingto claim 15 wherein the ratio of primary to co-surffactant is between20:1 and 50:1.
 21. The composition according to claim 20 wherein theratio of primary to co-surfactant is about 30:1.
 22. The compositionaccording to claim 18 wherein the amount of emulsifier is less than 6%.23. The composition according to claim 18 wherein one or moreantioxidants is first dispersed in the emulsifier mixture, and theamount of antioxidant is 0.3-0.5%.
 24. The composition according toclaim 23 wherein ascorbic acid, alpha-tocopherol or both are present.25. A beverage comprising a composition according to claim
 18. 26. Amethod of administration of a biologically active oil composition to ahuman or animal in need thereof, which method comprise administering tosaid human or animal a composition according to claim
 18. 27. Acomposition according to claim 11 wherein the antioxidant is firstdispersed in the emulsifier mixture.
 28. The composition according toclaim 18 wherein the biological oil further includes a consumable oressential oil.